Opioid and human immunodeficiency virus (HIV) interactions can occur in individuals who abuse intravenous drugs, or for those treating pain stemming from HIV infection. Currently, many studies support the notion that opioids may accelerate the progression of HIV-associated dementia, a neurological disorder resulting from HIV entry and infection of the central nervous system (CNS). However, our data suggest that the opioid morphine may in fact, be protective. My overall goal is to demonstrate that morphine, which stimulates the release of a neuroprotective chemokine CCL5 within the CNS, can mediate or prevent toxicity induced by HIV viral protein gp120Bal. The specific Aims of the proposed research are to: 1) determine in vivo CCL5 expression after distinct morphine treatment paradigms 2) prove that morphine is neuroprotective against gp120Bal in vivo and demonstrate that CCL5 is necessary for this protection. It has been established that <-opioid receptor stimulation of mixed neuronal cultures results in the synthesis and release of CCL5. Consequently, Aim 1 will comprise of in vivo studies in which Sprague-Dawley rats will be exposed to an array of morphine treatment paradigms to emulate conditions of opioid use. The resultant levels of the chemokine CCL5, will be assessed after each paradigm. Methods I will employ include animal treatments, behavioral analysis, dissections, and CCL5 analysis by the enzyme linked immunosorbant assay (ELISA). Gp120Bal and CCL5 both bind to the receptor CCR5. Therefore I would expect that the treatment paradigm which increases the expression of CCL5 would reduce gp120Bal toxicity. Aim 2 will determine neuroprotection or toxicity from gp120Bal after morphine treatment in vivo. Animals will be stereotaxically injected with gp120Bal prior to the start of the morphine treatment paradigms and apoptotic cell death will be assessed by caspase-3 and terminal UTP nick end labeling (TUNEL). To fulfill this Aim I will employ stereotaxic surgeries, immunohistochemistry, and will be trained in stereology. Furthermore to confirm that CCL5 is the mediator of protection from morphine, I will utilize shRNA and recombinant adeno-associated virus (rAAV) technology to down regulate or overexpress CCL5 in vivo, respectively. For this sub-Aim, I will be trained in viral vector technology. This proposal intends to enhance my training in the neurobiology of drug abuse, as well as to progress the understanding of a new property of morphine. Moreover the mechanistic studies proposed will likely identify intermediaries which can be targeted for the development of future therapeutics.